Turning y axis upside down in MATLAB

Solution 1:

The 'YDir' axes property can be either 'normal' or 'reverse'. By default it is 'normal' for most plots, but some plots will automatically change it to 'reverse', such as the image or imagesc functions.

You can set the y-axis direction of an axes with either the set function or dot indexing (in newer MATLAB versions):

h = gca;  % Handle to currently active axes
set(h, 'YDir', 'reverse');
% or...
h.YDir = 'reverse';

I'm baffled by some of the other answers saying that the 'YDir' property has somehow disappeared or is giving an error. I haven't seen any such behavior in versions of MATLAB from 2013, 2014, or 2016. There are only two potential pitfalls I came across:

• The property can't be set with a cell array, only a character string:

  >> set(gca, 'YDir', {'reverse'});
  Error using matlab.graphics.axis.Axes/set
  While setting property 'YDir' of class 'Axes':
  Invalid enum value. Use one of these values: 'normal' | 'reverse'.
  

  although this works:

  set(gca, {'YDir'}, {'reverse'});  % Property name is also a cell array
  

• The gca function can't be used interchangeably as a handle when performing dot indexing (which is why I first saved it to a variable h in the above example):

  >> gca.YDir
  Undefined variable "gca" or class "gca.YDir". 
  >> gca.YDir = 'reverse'  % Creates a variable that shadows the gca function
  gca = 
    struct with fields:
  
      YDir: 'reverse'
  

Finally, if you want some code that will toggle the 'YDir' property no matter what its current state is, you can do this:

set(gca, 'YDir', char(setdiff({'normal', 'reverse'}, get(gca, 'YDir'))));
% or...
h = gca;
h.YDir = char(setdiff({'normal', 'reverse'}, h.YDir));

Solution 2:

The command

axis ij

Will also reverse the Y-axis (negative above x-axis; positive below).

Solution 3:

The solutions on the top of the stack did not work for me,

• imagesc(x,y,data) % results in a flipped plot, the y axis is upside down

• set(gca,'YDir','reverse'); % gives an error

• axis ij; % still gives the flipped plot

what did work was the following:

imagesc(x,y,data); axis xy;  % results in the correct plot

The YDir property has vanished in the matlab version (2013 and up) that I'm using.

Solution 4:

To update this answer, since it is still a popular Google result: As of R2014a, the correct way to flip the Y axis is the following:

>> axis ij

This change can be reversed through the following command

>> axis ji

To flip the X or Z axes, do the following

set(gca,'XDir','reverse');

set(gca,'ZDir','reverse');

Personally, I think it would have been easier to keep the YDir option, but what do I know.